The Difference Engine as designed and partially built in the 1830’s was a mechanical device of some 4000 moving parts that could perform automated mathematical functions (logarithmic, trigonometric and polynomial). The brain child of mathematician/inventor Charles Babbage, the machine was never completed during his lifetime. However in the late 1980’s a working model was produced to celebrate Babbage’s work—remaining largely loyal to the original design and production abilities of the 19th century craftsmen. This book details both the original genius of Babbage’s life and work as well the recreation of it over 150 years later. Unfortunately, the modern part of the book and the building of the machine is more compelling than the Babbage part. The author was involved in that part himself, and that closeness to the story gives the tale more life. The detailing of Babbage’s life shifts gears, often awkwardly, between being straight bio and workshop treatise. There is a level of reality created by going back and forth from Babbage’s funding problems and frustrations and his work in the shop, but I felt it diminished the work in the shop greater than necessary. I would have appreciated more effort explaining the theories and processes involved in the ground breaking work and less on what an irritation Babbage could be to those around him. The idea of someone attempting to build a computer in the early part of the 19th century is fascinating (as anyone interested in the creative genre of steampunk already knows), and this book does percolate on occasion but not nearly as often as I wanted. The parallel frustrations of Babbage in the 1830’s and the author in the 1980’s at attempting to get their machines built was interesting too but by the time the machine was built, I was ready to move on.